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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
               //1 定义一个getSum()函数
       function getSum () {
           var sum = 0;
           for (var i = 1; i <= 100; i++) {
               sum += i;
           }
           document.write('1到100个数相加和是：'+sum);
       }
       //2 调用getSum()函数
       getSum();
    </script>
</body>
</html>